An end-user may access IPTV (Internet Protocol Television)-services from different types of UEs (User Equipments), such as e.g. a TV, a PC (Personal Computer) or a mobile phone, for example via the IMS (Internet Protocol Multimedia Sub-system), provided that the UE has suitable functionality, which may be specified e.g. according to the Open IPTV-Forum-specification.
Conventionally, a bandwidth can be reserved during set-up of a session, such as e.g. a Video on Demand-session, which is using a unicast stream, or a conventional television broadcast session, which is using a multicast stream. The bandwidth reservation will ensure that there is enough bandwidth both in “the last mile” to the subscriber and in the aggregation network in order to provide the user with an adequate experience, without any disruptions or disturbances of the service. Further, two sessions may together exceed the available bandwidth over the last mile. This will cause the packets in the two sessions to compete with each other, and result in that some packets will be discarded in both sessions. Thus, it is important that a new session is not allowed to affect the existing sessions, once a bandwidth has been reserved for the existing sessions.
Media content can be downloaded from a media content server to a UE, acting as a client terminal, e.g. by progressive downloading, in which the media content is stored in a local buffer in order to enable a play-out of the media file before the downloading is complete, by streaming downloading, in which the media content is streamed from the content server at the rate of the play-out and involving no storing, or by adaptive streaming downloading, in which the content can be downloaded at different bitrates. In a similar way, media content can be uploaded from a UE to a content server, and may subsequently be shared to other users using downloading.
However, a conventional HTTP progressive downloading of media content only supports a best-effort Quality of Service, i.e. no guaranteed QoS, and the bandwidth may not be the maximum bandwidth. Consequently, in case the resolution of the media content is high and the network has a limited bandwidth, the user experience of the play-out out may be poor. For example, media content downloaded from the well-known website YouTube is displayed while it is being downloaded, using only best-effort Quality of Service. If the resolution is limited and not too high, the available bandwidth may be sufficient, and the user experience of the played-out media content acceptable. However, otherwise the user experience may be poor.
Further, a correct playback of a progressively downloaded media file requires that the UE, i.e. the client terminal, is able to buffer a large amount of media content.
Thus, it still presents a problem to achieve an acceptable user-experience of played-out media content.